Analysis Of The Melting Mechanism And Fault Prevention Strategy Of Drop-out Fuse
High Voltage Fuse is the core protection device of the distribution network. Its abnormal fusing will directly affect the reliability of power supply and equipment safety. Based on the operation data of the power system, this article analyzes the typical causes of fuse failures and proposes targeted prevention and control measures.
1. Overcurrent fuse mechanism
... The measured data show that the fuse time is approximately 300 seconds at 1.2 times the rated current, and when the current reaches 1.5 times the rated current, the fuse time is sharply reduced to 60 seconds. A case in an industrial park shows that the continuous overload caused by the insulation damage of the low-voltage side cable of the transformer caused the fuse to melt within 7 minutes.
... ... Electrochemical corrosion tests show that the annual corrosion rate of fuses in coastal areas is 0.12mm/year, which causes its rated current carrying capacity to drop by 20%. Statistics from a coastal substation show that the failure rate of fuses that have been in service for 8 years is 3.2 times higher than that of new products.
... ... Third, environmental factors and installation defects
... When the humidity is greater than 85%RH, leakage current will be generated inside the fuse due to condensation. According to statistics from a rainy area, such faults account for 62% of seasonal fuses.
... ... - 12 times, and the duration is 200 - 400 milliseconds. Electromagnetic transient simulation confirms that 6% of the fuse failures are directly related to frequent switching operations. It is recommended to install an RC absorption device to limit the operating overvoltage to less than 2.5p.u.
... ... Smart monitoring application
... ... ... Standard installation process standards: fuse bending radius ≥ 5d (wire diameter), connection terminal torque control within 25-35N·m, fuse axis verticality error < 2°. After the overhaul, 30 mechanical property tests are required.
